The present invention relates generally to video tape recorders, and in particular to such recorders including a video head driving unit which permits slow-motion and stop-motion video images during the so-called "trick play mode".
Attempts which have hitherto been made to provide the feature of trick play mode involve the use of a horizontal yoke carrying at each end thereof a video transducer head. The yoke is pivotally mounted within a rotary drum so that it rotates with the drum while moving pivotally about a transverse axis to displace the video heads in vertical position during trick play mode. An electromagnetic arrangement is provided which responds to a control signal by tilting the yoke to a desired angle so that the video heads are displaced from the horizontal and shifted in position for repeated or skipped tracing of the tracks. A prior attempt involves the use of a spring for restoring the yoke upon de-energization of the electromagnetic arrangement. In this case, the latter arrangement needs to overcome the spring action when moving the yoke. However, the spring tension needs to be sufficient to withstand vibrations which are likely to occur for video tape recorders of the portable type when videotaping moving objects. Difficulties therefore arise in satisfying these conflicting factors.
One approach would be to secure the pivot point of the yoke to a leaf spring, while preventing contact between points of the pivot point and leaf spring. However, the spring tends to exhibit a hysteresis characteristic. This causes the yoke and hence the video heads to remain displaced from the horizontal home position even when the control signal is removed from the yoke operating arrangement.